Unfortunately, the Sitebuilder and Homestead logins are one in the same and there's currently no way to set up other users within the same account to have different permissions. I'm so sorry about that! Once someone has the login info, they have access to everything within the account.
I wish I had better news for you! Please be sure to submit this as an idea, so our developers know that there is a need for this.
Thanks Aubrey. I will surely submit this as a suggestion to the development team. In my situation, I maintaint the website of our municipality and having access to the emails is not legally acceptable.